It has been suggested that stimulation of glucose transport activity in a variety of cell types may involve the production of hydrogen peroxide or reactive oxygen radicals. In this project, a variety of agents known to produce hydrogen peroxide and/or superoxide anion intracellularly will be tested for their effects on glucose transport in rat thymocytes. The inhibitory effects of free radical scavengers such as hydroquinone on transport stimulation will also be examined. In addition, purified plasma membranes will be prepared from rat thymocytes and examined for the presence of redox system such as NADH oxidoreductase. Finally, superoxide dismutase levels will be assayed in cells that have been exposed to a variety of transport stimulating agents. It is hoped that the results of these studies will shed light on the possible participation of redox reactions in glucose transport regulation.